Ribulose-1,5-bisphosphate oxygenase (RuBisCO) protein fibers and a method of producing them are disclosed herein. The method of producing one or more RuBisCO protein fibers including obtaining RuBisCO, for example from tobacco, combining the RuBisCO with one or more plasticizers, heating the combination of the RuBisCO and the one or more plasticizers up to about 140 degrees C., filtering the heated combination through an about 20 μm filter, and passing the filtered combination through an orifice to produce one or more RuBisCO protein fibers.